643399679 has 8 divisors (see below), whose sum is σ = 729360240. Its totient is φ = 562648896.

The previous prime is 643399643. The next prime is 643399693. The reversal of 643399679 is 976993346.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 643399679 - 2¹⁶ = 643334143 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643399609) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1302182 + ... + 1302675.

It is an arithmetic number, because the mean of its divisors is an integer number (91170030).

Almost surely, 2^643399679 is an apocalyptic number.

643399679 is a deficient number, since it is larger than the sum of its proper divisors (85960561).

643399679 is a wasteful number, since it uses less digits than its factorization.

643399679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2604889.

The product of its digits is 6613488, while the sum is 56.

The square root of 643399679 is about 25365.3243424956. The cubic root of 643399679 is about 863.2970959018.

The spelling of 643399679 in words is "six hundred forty-three million, three hundred ninety-nine thousand, six hundred seventy-nine".